Analysis of the designs of integrated circuits can be performed to quantify fault isolation. However, such analysis is often time consuming and labor intensive. Furthermore, such analysis is often only performed to discover potential flaws in the IC designs. As a result, such analysis is not well suited to address issues such as determining a fault cost for a structure of the IC, e.g., a fault cost for a particular type of multiplexer in the IC. For example, a fault cost can be defined broadly as a number of functional faults that need to occur before a structure in the IC will fail. Using a multiplexer as an example, a fault cost may indicate a number of transistors that will need to fail before an input of the multiplexer is leaked unintentionally to the output of the multiplexer.